01-21-2010, 01:28 PM
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Originally Posted by redchigh
the bulbs are bluish, like cool white. i'll check the package and make sure they're not actinic but i dont think they are. is it possible to just use cool white bulbs? or a mixture of cool white and warm white?
i eventually want cabomba, straight or twisted vallis, egeria densa, and hornwort. maybe a brazil sword at some point.
"Cool white" is normally just a tad more blue than regular daylight or full spectrum, but so close it is basically full spectrum with a tad more blue--if that all makes sense. The kelvin rating is sometimes useful, sometimes not. The Phillips Daylight Deluxe I have is cool blue in colour, but the rating is 6500K. My Life-Glo full spectrum at 6700K is not as "cool" in appearance. I would not use a tube higher than 7000K without something with more red (5500-6500) tin combination to balance.
In a study on plant growth under different types of fluorescent lighting, plants grew best under a mixture of full spectrum and cool white. Second best was under cool white. Third was full spectrum. What this says to me is that cool white obvious is good plant light, but adding a touch of the warmer red does make a slight difference.
You might wonder then why I recommend full spectrum alone over single tube tanks; simply, appearance. Cool white is "cool" to the eye, and while my personal preference tends to cooler white than warmer, I like the fish and plant colours to be natural which they are if there is sufficient green (and red) in the mix. Over dual-tube tanks we can have the best, which is why I always suggest dual-tube T8 lighting over single tube T5; it leaves you this option.